Types of Surface Treatments for Metal Parts
Metal fabrication takes many forms. Shops large and small make parts for autos, airplanes, and machinery. Metal parts benefit from finishing processes that remove imperfections and prepare them for coatings of paint. Different types of surface treatments for metal parts prevent or delay corrosion, metal fatigue, add a decorative shine or texture, change electrical conductivity, or reduce friction. There are hundreds of coatings or chemical and physical processes applied to different types of metal to improve them in some way.
Galvanizing, Plating, and Anodizing
These processes alter the surface of metal by coating, covering, or changing the composition of the metal in some way. Galvanizing is the most familiar: steel or iron parts are dipped into melted zinc to form a surface more resistant to corrosion. Electroplating applies a thin coating of metal to the surface by introducing a positive electrical charge into a solution of dissolved metal while charging the parts to be coated with a negative current. In electroless plating, the part acts as a catalyst to create a reaction with the material that forms the thin plate or film. Anodizing is another process that uses electrical current to thicken the natural oxidization on the surface of the particular metal, usually aluminum.
Peening, Grinding, Lapping, and Deburring
These are all types of surface treatments for metal parts that may remove bits of metal or reshape a part. Peening can strengthen or weaken metal, or just change its look. Hammering or blasting with shot or lasers produces a peened surface. Grinding is just what it sounds like – using a tool, usually a grinding wheel, to physically polish, smooth, or thin the surface. Lapping is a form of grinding where an abrasive is placed between two surfaces as they are rubbed together. Finally, deburring is a type of polishing or finishing that removes metal imperfections using abrasive media in tumbling or vibratory finishing equipment.
Powder Coating and Painting
Powder coating or thermal spraying uses heat to melt and apply a plastic powder, or to fuse a metal or ceramic onto the surface of the metal undergoing treatment. Paint applies color and hinders corrosion. Painting methods may include dipping, spraying, or brushing. Robotic painting ensures consistency in the painted finish for cars and trucks. These processes can also improve heat resistance, increase friction or grip properties, and prevent or discourage marine life from adhering to surfaces in water environments.